<!--
插件来自：
https://github.com/826327700/vue-piczoom
由于使用npm安装方式报错，所以放到本地
-->
<template>
  <div class="magnifier-box" :class="[vertical && 'vertical']" :ref="id" @mousemove="mousemove" @mouseover="mouseover" @mouseleave="mouseleave">
    <img v-show="showImg" :src="imgUrl" alt="">
    <div class="mouse-cover"></div>
    <div class="edit-wrap" v-if="showEidt">
      <span class="rotate-left" @click="rotate('left')"></span>
      <span class="rotate-right" @click="rotate('right')"></span>
    </div>
  </div>
</template>

<script>
  export default {
    name: 'PicZoom',
    props:{
      scale:{
        type: Number,
        default: 2.5
      },
      url:{
        type: String,
        required: true
      },
      bigUrl:{
        type: String,
        default: null
      },
      scroll:{
        type: Boolean,
        default: false
      },
      showEidt:{
        type: Boolean,
        default: false
      }
    },
    data () {
      return {
        id: null,
        cover: null,
        imgbox: null,
        imgwrap: null,
        orginUrl: null,
        bigImgUrl: null,
        bigOrginUrl: null,
        imgUrl: null,
        img: null,
        canvas: null,
        ctx: null,
        rectTimesX: 0,
        rectTimesY: 0,
        imgTimesX: 0,
        imgTimesY: 0,
        init: false,
        step: 0,
        bigStep: 0,
        vertical: false,
        showImg: true
      }
    },
    created(){
      var $chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678';    /****默认去掉了容易混淆的字符oOLl,9gq,Vv,Uu,I1****/
      var maxPos = $chars.length;
      var str = '';
      for (let i = 0; i < 10; i++) {
        str += $chars.charAt(Math.floor(Math.random() * maxPos));
      }
      this.id=str
      this.imgUrl = this.url
      this.orginUrl = this.url
      this.bigImgUrl = this.bigUrl
      this.bigOrginUrl = this.bigUrl
    },
    watch:{
      url: function(val){
        this.imgUrl = val
        this.orginUrl = val
        this.initTime()
      },
      bigUrl: function(bigUrl){
        this.bigImgUrl = bigUrl
        this.bigOrginUrl = bigUrl
        this.initTime()
      }
    },
    mounted(){
      this.$nextTick(() => {
        this.initTime()
      })
    },
    methods: {
      initTime() {
        this.init = false
        let box = this.$refs[this.id]
        this.imgbox = box
        this.cover = box.querySelector('.mouse-cover')
        this.cover.style.width = (this.imgbox.offsetWidth / this.scale) + 'px'
        this.cover.style.height = (this.imgbox.offsetHeight / this.scale) + 'px'
        this.cover.style.left = '-100%'
        this.cover.style.top = '-100%'
        this.imgwrap = box.querySelector('img')
        let imgsrc;
        if(this.bigImgUrl){
          imgsrc = this.bigImgUrl
        }else{
          imgsrc = this.imgUrl
        }

        this.img = new Image()
        this.img.src = imgsrc
        this.img.onload = () => {
          this.rectTimesX = (this.imgbox.offsetWidth / this.scale) / this.imgwrap.offsetWidth,
            this.rectTimesY = (this.imgbox.offsetHeight / this.scale) / this.imgwrap.offsetHeight
          this.imgTimesX = this.img.width / this.imgwrap.offsetWidth,
            this.imgTimesY = this.img.height / this.imgwrap.offsetHeight
          this.vertical = this.img.width < this.img.height
          this.init = true
        }
        if(this.canvas){
          this.canvas.parentNode.removeChild(this.canvas)
          this.canvas = null
        }
        this.canvas = document.createElement('canvas')
        this.canvas.className = 'mouse-cover-canvas'
        this.canvas.style.position = 'absolute'
        this.canvas.style.left = this.imgbox.offsetLeft + this.imgbox.offsetWidth + 10 + 'px'
        this.canvas.style.top = this.imgbox.offsetTop + 'px'
        this.canvas.style.border = '1px solid #eee'
        this.canvas.style.zIndex = '99999'
        this.canvas.height = this.imgbox.offsetHeight
        this.canvas.width = this.imgbox.offsetWidth
        this.canvas.style.display = 'none'
        document.body.append(this.canvas)
        this.ctx = this.canvas.getContext("2d")
        this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height)
      },
      initBox(){
        this.showImg = false
        this.canvas.style.display = 'none'
        let box = this.$refs[this.id]
        let imgsrc;
        if(this.bigImgUrl){
          imgsrc = this.bigImgUrl
        }else{
          imgsrc = this.imgUrl
        }
        this.img = new Image()
        this.img.src = imgsrc
        this.img.onload = () => {
          this.vertical = this.img.width < this.img.height
          this.showImg = true
          let thumb = box.querySelector('img')
          setTimeout(() => {
            this.rectTimesX = (this.imgbox.offsetWidth / this.scale) / box.querySelector('img').offsetWidth,
              this.rectTimesY = (this.imgbox.offsetHeight / this.scale) / box.querySelector('img').offsetHeight
          }, 20)
        }
      },
      mousemove(e){
        if(!this.init){
          return false
        }
        let _this = this
        //获取实际的offset
        function offset(curEle){
          var totalLeft = null, totalTop = null, par = curEle.offsetParent
          //首先加自己本身的左偏移和上偏移
          totalLeft += curEle.offsetLeft
          totalTop += curEle.offsetTop
          //只要没有找到body，我们就把父级参照物的边框和偏移也进行累加
          while(par){
            if(navigator.userAgent.indexOf("MSIE 8.0") === -1){
              //累加父级参照物的边框
              totalLeft += par.clientLeft;
              totalTop += par.clientTop
            }

            //累加父级参照物本身的偏移
            totalLeft += par.offsetLeft;
            totalTop += par.offsetTop
            par = par.offsetParent;
          }

          return{
            left: totalLeft,
            top: totalTop
          }
        }

        function getXY(eve) {
          return {
            x : eve.clientX - (_this.cover.offsetWidth / 2),
            y : eve.clientY - (_this.cover.offsetHeight / 2)
          };
        }
        let oEvent = e || event;
        let pos = getXY(oEvent);
        let imgwrap = offset(this.imgwrap)
        let range = {
          minX:imgwrap.left,
          maxX:imgwrap.left + this.imgwrap.offsetWidth - this.cover.offsetWidth,
          minY:imgwrap.top - (document.documentElement.scrollTop || document.body.scrollTop),
          maxY:imgwrap.top - (document.documentElement.scrollTop || document.body.scrollTop) + this.imgwrap.offsetHeight - this.cover.offsetHeight
        }
        if(pos.x > range.maxX){
          pos.x = range.maxX
        }
        if(pos.x < range.minX){
          pos.x = range.minX
        }
        if(pos.y > range.maxY){
          pos.y = range.maxY
        }
        if(pos.y < range.minY){
          pos.y = range.minY
        }
        this.cover.style.left = pos.x+'px'
        this.cover.style.top = pos.y+'px'
        this.ctx.clearRect(0, 0, this.imgwrap.offsetWidth, this.imgwrap.offsetHeight)
        let startX = pos.x - (imgwrap.left - (document.documentElement.scrollLeft || document.body.scrollLeft)),
          startY = pos.y - (imgwrap.top - (document.documentElement.scrollTop || document.body.scrollTop))
        this.ctx.drawImage(this.img,startX * this.imgTimesX, startY * this.imgTimesY, this.img.width * this.rectTimesX, this.img.height * this.rectTimesY, 0, 0, this.imgbox.offsetWidth, this.imgbox.offsetHeight)
      },
      mouseover(e){
        if(!this.init){
          return false
        }
        e = e || event
        if(!this.scroll){
          e.currentTarget.addEventListener("mousewheel", function(ev){
            ev.preventDefault()
          }, false)

          e.currentTarget.addEventListener("DOMMouseScroll",function(ev){
            ev.preventDefault()
          }, false)
        }

        this.cover.style.display = 'block'
        this.canvas.style.display = 'block'
      },
      mouseleave(){
        if(!this.init){
          return false
        }
        this.cover.style.display = 'none'
        this.canvas.style.display = 'none'
      },
      rotate(direction){
        var orginImg = new Image()
        orginImg.crossOrigin = "Anonymous";
        orginImg.src = this.orginUrl
        orginImg.onload = () => {
          this.rotateImg(orginImg, direction, this.step)
        }
        if(this.bigOrginUrl){
          var bigOrginImg = new Image()
          orginImg.crossOrigin = "Anonymous"
          bigOrginImg.src = this.bigOrginUrl
          bigOrginImg.onload = () =>{
            this.rotateImg(bigOrginImg, direction, this.bigStep, true)
          }
        }
      },
      rotateImg(img, direction, step, isBig = false){
        var min_step = 0;
        var max_step = 3;
        if (img == null) return;
        //img的高度和宽度不能在img元素隐藏后获取，否则会出错
        var height = img.height
        var width = img.width

        if (step == null) {
          step = min_step
        }
        if (direction == 'right') {
          step++;
          //旋转到原位置，即超过最大值
          step > max_step && (step = min_step);
        } else {
          step--;
          step < min_step && (step = max_step);
        }
        var canvas = document.createElement('canvas')

        //旋转角度以弧度值为参数
        var degree = step * 90 * Math.PI / 180
        var ctx = canvas.getContext('2d')
        canvas.width = height
        canvas.height = width
        ctx.rotate(degree)
        ctx.drawImage(img, 0, -height)
        switch (step) {
          case 0:
            canvas.width = width
            canvas.height = height
            ctx.drawImage(img, 0, 0)
            break
          case 1:
            canvas.width = height
            canvas.height = width
            ctx.rotate(degree)
            ctx.drawImage(img, 0, -height)
            break;
          case 2:
            canvas.width = width
            canvas.height = height
            ctx.rotate(degree)
            ctx.drawImage(img, -width, -height)
            break
          case 3:
            canvas.width = height
            canvas.height = width
            ctx.rotate(degree)
            ctx.drawImage(img, -width, 0)
            break
        }
        var newImg=canvas.toDataURL()

        if(isBig){
          this.bigImgUrl=newImg
          this.bigStep=step
          this.initBox()
        }else{
          this.imgUrl = newImg
          this.step = step
          this.$nextTick(() => {
            this.initBox()
          })
        }
      }
    }
  }
</script>

<style lang="scss" scoped>
  .magnifier-box{
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    position: relative;
    .edit-wrap{
      position: absolute;
      top: 5px;
      right: 0;
      z-index: 9999999;
      background: rgba(0,0,0,0.4);
      padding: 5px 15px 0 15px;
      border-radius: 15px;
      $icon_rotate: '';
      .rotate-left{
        display: inline-block;
        cursor: pointer;
        width: 16px;
        height: 16px;
        background: url($icon_rotate);
        background-size: 100% 100%;
        -moz-transform:scaleX(-1);
        -webkit-transform:scaleX(-1);
        -o-transform:scaleX(-1);
        transform:scaleX(-1);
        /*IE*/
        filter: FlipH;
      }
      .rotate-right{
        margin-left: 10px;
        cursor: pointer;
        display: inline-block;
        width: 16px;
        height: 16px;
        background: url($icon_rotate);
        background-size: 100% 100%;
      }
    }
    img{
      width: 100%;
    };
    .mouse-cover{
      position: fixed;
      background-color: rgba(0,0,0,0.5);
      cursor:move
    };
    .mouse-cover-canvas{
      position:fixed;
      left:100%;
      top:0;
      width:100%;
      height:100%;
    }
    &.vertical{
      img{
        height: 100%;
        width: auto
      }
    }
  }
</style>
